OPTICAL ADD/DROP MULTIPLEXER

摘要

The invention concerns an optical add/drop multiplexer for the node of a telecommunications system. In the telecommunications system wavelength multiplexing is used to transmit along an optical fiber a main system signal including several different signals. The signals are transmitted each with its own wavelength and of the signals it is possible to drop and to add desired chosen optical signals having different wavelengths ( lambda 1... lambda N,(N>1)). The add/drop multiplexer includes a group formed by direction selective organs and wavelength selective organs. Several such groups are connected to each other by connecting to each other gates of direction selective organs in the group. At least some of the other gates of the direction selective organs in the groups are used as gates of the add/drop multiplexer, so that the type of each gate to be used is chosen from a set including a unidirectional add gate, a unidirectional drop gate and a bi-directional add/drop gate. In addition, to each bi-directional add/drop gate is connected a direction selective organ in order to separate different directions from each other. In the optical add/drop multiplexer it is hereby possible to choose the configuration of the add/drop multiplexer by combining groups in the desired way with each other, and within the chosen configuration the outputs and inputs of the different wavelengths can be chosen so that those wavelengths which experience most attenuation in the network will experience correspondingly less attenuation in the optical add/drop multiplexer.